Examples of an SIP based message service include Instant Messaging (IM), Push-to-Talk Over Cellular (PoC), Multimedia Messaging (MMS) and so forth. Methods used for sending messages in such an SIP based message service include the following ones.
First, the IETF standard RFC 3428 proposes the MESSAGE method, an extension to the Session Initiation Protocol (SIP) that allows the transfer of Instant Messages. Since an MESSAGE request in the MESSAGE method is an extension to SIP, it inherits all the request routing and security features of that protocol. MESSAGE requests carry the content in the form of MIME body parts. MESSAGE requests do not themselves initiate a SIP dialog. Under normal usage, each Instant Message stands alone, much like pager messages. MESSAGE requests may be sent in the context of a dialog initiated by some other SIP request.
The Message Session Relay Protocol (MSRP) is a protocol for transmitting a series of related instant messages in the context of a session. MSRP is a text-based, connection-oriented protocol for exchanging arbitrary (binary) MIME content, especially instant messages.
The IETF standard RFC 3903 defines a new SIP method, that is, the PUBLISH method, an extension to SIP for publishing event state used within the SIP Events framework. PUBLISH is similar to REGISTER in that it allows a user to create, modify, and remove state in another entity which manages this state on behalf of the user. The PUBLISH request may contain a body, which contains event state that the client wishes to publish. The content format and semantics are dependent on the event package identified in the Event header field.
The IETF standard RFC 3265 defines a new SIP method, that is, the NOTIFY method, an extension to SIP to inform subscribers of changes in state to which the subscriber has a subscription. Subscriptions are typically put in place using the SUBSCRIBE method. However, it is possible that other means have been used.
The IETF standard RFC 3265 defines a new SIP method, that is, the SUBSCRIBE method, an extension to SIP used to request current state and state updates from a remote node. When a subscriber wishes to subscribe to a particular state for a resource, it forms a SUBSCRIBE message. If the initial SUBSCRIBE represents a request outside of a dialog (as it typically will), its construction follows the procedures outlined in SIP RFC 3261 for UAC request generation outside of a dialog. The subscriber can expect to receive a NOTIFY message from each node which has processed a successful subscription or subscription refresh.
The IETF draft standard draft-ietf-simple-xcap-07 defines the Extensible Markup Language (XML) Configuration Access Protocol (XCAP). XCAP allows a client to read, write and modify application configuration data, stored in XML format on a Server. XCAP maps XML document sub-trees and element attributes to HTTP URIs, so that these components can be directly accessed by HTTP. The Client operations allowed by this protocol include Create or Replace a Document, Delete a Document, Fetch a Document, Create or Replace an Element, Delete an Element, Fetch an Element, Create or Replace an Attribute, Delete an Attribute, Fetch an Attribute.